Time-element device



Iune 24 1924. 1,499,178

R. H. M LAlN TIME ELEMENT DEvIcE Filed June 4. 1919 Sh 1-Sh t 1 H 2 r-fig. 88

T) ventor Robert H Mc Lain,

W QM E M His fTttorfieg.

June 24, 1924. 1,499,178

R. H. M LAIN TIME ELEMENT DEVICE Filed June 24 1919 2 Sheets-5heet 2 Fig.5.

Fig.6.

; nventor-z Rob rt H. McLain.

His Attorney.

Patented June 24, 1924.

UNITED STATES PATENT OFFICE.

ROBERT H. MoLAIN, OF SCHENECTADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

TIME-ELEMENT DEVICE.

Application filed June 24, 1919. Serial No. 306,370.

To all whom it may concern.

Be it known that I, ROBERT H. MoLAIN, a citizen of the United States, residing at Schenectady, county of Schenectady, State of New York, have invented certain new and useful Improvements in Time-Element Devices, of which the following is a specification.

My invention relates to time element devices for use in connection with the control of electric circuits and has for one of its objects the provision of an improved device of this character.

Time element devices are ordinarily used to delay the operation of electric switches whereby electric circuits may either be opened or closed as desired, as, for instance, to interpose a definite time interval between the closing of motor starting switches whereby the motor will come up to full operating speed in a certain interval of time, or to delay for a certain small interval of time the opening of an electric circuit in response to abnormal circuit conditions such as an overload on the circuit or a failure of voltage. 1

One of the objects of my invention is to provide a timeelement device which is simple and cheap to manufacture, positive lIl action, easily adjustable, and one which when adjusted for a certain time interval will always operate to give that time interval without the necessity of further adjustment.

In carrying my invention into efi'ect I employ a fiy-wheel, preferably in the form of a disc, which is biased to one position and rotatable to another position, the rotation of which from the one position to the other position provides the desired time interval in the control of electric circuits. The fiywheel is biased to one position in any suitable manner, as by unbalancing the same, and is held at the unstable position against its bias to the stable position by any suitable means. When desired, it is released so as to rotate to the stable position, the time consumed in rotating from the unstable to the stable position being the time interval provided for delaying the operation of electric switches. The fly-wheel has a tendency to assume the position of stable equilibrium and when released from the unstable position will slowly start to move to the stable position by reason of its inertia effect. Such a device provides an absolute and definite time interval which may be adjusted, as for instance by varying the force tending to rotate the fly-wheel or by shifting or varying the out-of-balance weight where the fiy wheel is made unbalanced, or by varying the effective are through which the flywheel operates. The time interval may also be varied by arresting or retarding the rotation of the fly-wheel in response to predetermined conditions. When my device is used for effecting the automatic acceleration of an electric motor, this may be efiected responsively to the current taken by the motor, 7

so that in case the motor current is above a predetermined value the disc will not rotate to the stable position until the current has dropped to the predetermined value, thereby providing a device whereby in case the motor current is less than the predetermined value the step by step acceleration will proceed with a definite time interval interposed between each step, but in case the motor current at any step is in excess of this predetermined value the time interval will beincreased until the current has dropped. This provides a combined time element and current limit device having advantages which will be readily understood by those skilled in the art. My arrangement is very simple and cheap to manufacture and when once adjusted there is no danger of getting out of adjustment or being afiected by externalv conditions.

Other objects and purposes of my invention will appear in the course of the following specification in which I have shown my invention embodied in concrete form for purposes of illustration.

In the accompanying drawings, Fig. 1 is a side elevation partly in section of my time element device in an open circuit position and of the operating and braking magnets; Fig. 2 is a view similar to that shown in Fig. 1 with the fly-wheel disc in a closed circuit position; Fig. 3 is a front elevation of my time element device of Fig. 2; Fig. 4 is a diagram of the circuits in a system for accelerating an induction motor in which my invention is used as a time element and current limit relay; Fig. 5 is a side elevation fied diagram of the same used to control a transmission circuit to prevent overloads on the line.

Referring to Figs. 1, 2 and 3, the flywheel disc 1 is rotatably mounted on the rod 2, screwed or otherwise made fast to the lug 3 projecting from the wall of the enclosing casing 4. In order to reduce the friction of rotation, roller or ball bearings (not shown), or other anti-friction bearings are provided. The ,fly-wheel disk 1 is unbalanced and made pendulous, preferably by the removal therefrom of a portion of its mass near its periphery as by drilling a hole 5 therein, but it will be obvious that the fly-wheel may be made pendulous in any suitable manner, as, for instance, adding weights to the periphery or shifting the outof-balanceweight. The disc carries a con tact 6 electrically connected to the system in any suitable manner, as by an insulated conductor as shown, and is arranged to engage a stationary contact 7 which is supported by a slightly yielding arm 8 rigidly secured to and insulated from the casing 4. The contact member 7 is likewise electrically connected to the system in any suitable manner. From the drawings it will be.observed that in Fi 1 the disc is in unstable equilibrium an when free to move from the position shown in F ig. 1, it will swing counter-clockwise and carry the contact 6 into engagement with contact 7, as indicated in Fig. 2. In order to stop the disc at such point of engagement and keep the circuit controlled by the contacts closed, a pin 9 which extends through the disc and projects on either side thereof, as shown in Fig. 3, engages the lug 10 projecting from the casing, said pin being so placed on the disc as to stop the swing of the latter at the desired point.

T 0 control the action of the fly-wheel disc herein described, I employ an electromagnet 11 of a well known form which controls the contacts 12. The armature 13 of this magnet is secured. to a shaft 14 as is also an arm 15 provided with a roller 16 arranged to engage a cam lever 17 secured to one end of a shaft 18 journaled in the casing 4. Secured at the opposite end of the said shaft 18 is a hook-shaped member 19 arranged to embrace within its sweep and engage one of the projecting ends of pin 9 and a pin 20 on the disc. The spring 21 biases the member 19 to the position shown in Fig. 1.

When the'electromagnet is not energized, which is the condition of the apparatus shown in Fig. 1, the center oi gravity of the disc is above its support 2, and the disc tends to swing counter-clockwise, but this movement is prevented by the engagement of the pin 20 by the book of member 19, this member being' biased toward the pin 20 by the coiled spring 21. At the same time the pin 22 is in contact with the stop 10, so that the disc is restrained in the position shown in Fig. 1. In this condition of the apparatus the roller 16 does not forcibly engage the free end of cam lever 17, while the con tact 6, carried by the disc, is by about of arc to the left of contact 7, and the circuit controlled by these contacts is therefore open.

If the electromagnetll is energized and its armature is attracted, the roller 16 bears forcibly upon levr 17 and turns the same and with it the member 19 against the tendency of spring 21, until these parts assume the positions shown in Fig. 2. By this movement of the member 19, the disc is released and swings counter-clockwise to the stable position, carrying pin 20 t0 the position indicated in Fig. 2, also the contact 6 is carried downwardly until it engages contact'T, whereby the circuit controlled by these contacts is closed, while pin 9 is carried upwardly until it strikes lug 10, whereby the further swing of the disc is arrested in its new position.

The condition of the apparatus shown in Fig. 1 is restored when the electromagnet is deenergized; its armature returns to its normally open position, the pressure. of roller 16 upon lever 17 is removed and this lever, together with the member 19, is turned by spring 21 toward the position shown in Fig. 1, first engaging pin 9 and turning the disc clockwise, whereby the contact 6 is separated from contact 7 and breaks the circuit at this point. In its further movement toward the position shown in Fig. 1 the member 19 engages pin 20 and carries this pin as well as pins 9 and 22, and contact 6, all of which are carried by the disc, to the positions shown in Fig. 1, the clockwise movement of the disc being limited by the pin 22 when it strikes the. lug 10. It will be observed that the force of the spring is thereby made the most effective since the member 19 first strikes the pin 9 which is near the periphery of the disc and the torque exerted is therefore great to separate the contacts. after which the pin 22 is engaged and the torque exerted is not so great since a large torque is not needed after the" contacts are separated.

It is obvious that the time interval between the energization ofelectromagnet 11 and the closing of the circuit by the disc is determined by several factors, among which may be mentioned the radius of the disc, the are 1 through which the disc is allowed to rotate, the weight of the disc and the out-of-balance weight. The time interval'may be adjusted by varying any one of these factors. In order to vary the are through which the disc rotates, I provide a number of holes in the disc, as, for example, holes 23 and'24, and insert the stop pin 22 in the desired hole,

therebyv altering the are through which the contact 6 must travel. It will also be observed that when the electromagnet 11 is deenergized the armature 13 is free to drop into the open position instantly and before the disc has overcome its inertia effect for the clockwise return rotation. The inertia effect of the disc does not retard the opening movement of the armature.

The magnet 25 is provided with a movable core 25 for engaging the periphery of the disc to retard or stop the rotation of the disc while rotating to the stable position at which the contacts 6 and 7 make engagement. This rovides a further means for varying the time interval. This magnet 25 may be energized responsively to the motor current so that the acceleration of the, motor may be under the control of the motor current.

In Fig. 4 I have shown my invention embodied in a system of control for a threephase induction motor of the slip ring type having starting resistance in "the motor secondary. This figure is very diagrammatic, and it is for the purpose of briefly explaining a use for my invention. The three-phase induction motor M is adaptedto be energized from the source of supply 26 by the closing of the pilot switch 27 to energize the coil 11' across one of the phases of the source and thereby close the switch contacts 12. The unbalanced fiy-wheel 1' is thereby released so as to rotate to the stable position so that the contact 6' may engage with the contact 7. If the current taken by the motor is of such a value that the current limit relay 28 is energized to close its contacts, the coil 25 will be connected across one of the phases of the source and thereby produce a friction drag on the fiy-wheel disc 1 and retard the movement of the fly-wheel disc or stop the rotation of the disc entirely so that the con tact 6 will not make engagement with the contact 7' until the speed of the motor M has increased so that the current taken by the motor has dropped to such a value that the current limit coil 28 will drop its contacts and thereby deenergize the coil 25. The coil 25' thus provides means whereby the acceleration of the motor is under the control of the motor current. The time consumed by the fly-wheel disc 1 in rotating from the unstable to the stable position introduces the desired time interval in the acceleration of the motor. As soon as these contacts make engagement, the winding 11 is energized across one of the phases of the sourceto close the switch contacts 12 and thereby short circuit the section B of the starting resistance in the motor secondary. This releases the fly-wheel disc 1" to rotate to the stable position in accordance with the manner previously explained. In case the motor current is in excess of the predetermined value, the current limit throttle 28 will again pick up its contacts and energize the coil 25 to retard or stop the rotation of the fly-wheel disc 1". 'VVhen the contacts 6 and 7 make engagement, the coil of electromagnet switch 29 is energized to close its contacts and short circuit the section B of the starting resistance and permit the motor to come up to full operating speed.

In Fig. 5 I have shown a form of my invention particularly adapted for use as a time element relay for disconnecting a translation device from a source of supply when the current taken by the device is in excess of a predetermined value for a definite interval of time. In this figure similar reference characters denote the same parts as those in Figs. 1, 2 and 3, and the operation of this relay is substantially the same as the operation of those shown in Figs. 1, 2 and-3. A particular description of Fig. 5 need not be given, since the operation will be understood in connection with a description of Fig. 6. The normally open oil switch 30 is adapted to connect a translation device (not shown) to a source of supply 31. In case the current taken by the translating device exceeds a predetermined value, the overload relay 32 will pick up its contacts and energize the coil 11 of the time element relay across the source of supply 33. This will release the fly-wheel disc 1 to rotate to the stable position, and if the overload on the translation device persists throughout the time required for the disc 1 to rotate from the unstable'to the stable position, the contacts 6 and 7 will make engagement and energize the coil 34 to release the detent 35 by attracting'the right-hand end of the detent against its bias to the position shown in the drawingso as to permit the contacts of the oil switch 30 to open in accordance with the bias produced by the spring 36. It, however, the overload does not persist for this definite interval of time, the overload relay 32 will drop its contacts and thereby deenergize the coil 11 ot the time element relay so as to permit the armature to drop open. This will cause the trigger 19 to move the fly-wheel disc 1 to its unstable position. By this arrangement I have provided means whereby momentary overloads in the translation device will not cause the opening of the oil switch, but only overloads which persist as long as the time interval provided by the rotation of the unbalanced fly-wheel disc 1 from the unstable to .the stable position will cause the opening of the oil switch.

In accordance with the provisions of the patent statutes, I have described the principle of operation of my invention, together with the apparatus which I now consider to represent the best embodiment thereof; but I desire to have it understood that the ap paratus shown is only illustrative, and that the invention can be carried out by other means.

\Vhat I claim as new and desire=to secure by Letters Patent of the United States, is 2-- 1. A time element device for controlling electric circuits comprising a rotatably mounted disc adapted to be held at one position against its bias to a second position, circuit making contacts controlled thereby at the second position, means for releasing the disc to permit the same to rotate to the second position in accordance with its bias, whereby a time interval in the control of the said contacts is introduced by the time taken by said disc in rotating from the first position to the second position, and means under the control of the first mentioned means for restoring the disc to the first position.

2. A time element device for controlling electric circuits comprising an unbalanced rotatably mounted fly-wheel adapted to be held at an unstable position, circuit controlling contacts controlled thereby, a member biased to one position for rotating the fiy- Wheel to an unstable position and for holding the same in an unstable position, and means for operating the said member against its bias to release the fly-wheel to permit the same to rotate to the stable position and control the said contacts, whereby a time interval in the control of the electric circuit is introduced by the time taken by said fly-wheel in rotating from the unstable to the stable position.

3. A time element device for controlling electric circuits comprising an unbalanced rotatably mounted fly-wheel, an electromagnet having a magnetic movable member, and an operating member controlled by the said magnetic member for rotating the fly-wheel to an unstable position and for releasing the fly-wheel to permit the same to rotate to the stable position and operate the said contacts, whereby a time interval in the control of the said contacts is introduced by the time taken by said fly-wheel in rotating from the unstable to the stable position.

4. A time element device for controlling electric circuits comprising an unbalanced rotatably mounted fly-wheel, circuit controlling contacts controlled thereby, a trigger biased to one position for rotating the flywheel to an unstable position and for holding the same in the unstable position, and an electromagnet for operating the said trigger against its bias to release the fiy-wheel to permit the same to rotate to the stable position and to control the said contacts, whereby a time interval in the control of the electric circuit is introduced by the time taken by said fiy-wheel in rotating from the unstable to the stable position.

5. A time element device for controlling electric circuits comprising an unbalanced rotatably mounted flywheel adapted to be held at an unstable position, switch mechanism controlled thereby at the stable position, means for releasing the flywheel to permit the same to rotate .to the stable position, whereby a time interval in the control of the said switch mechanism is introduced by the time taken by said flywheel in rotating from the unstable to the stable position,and means for varying the time interval.

(3. A time element device for controlling electric circuits comprising a rotatably mounted disc adapted to be held at one position againstits bias to a second position, switch mechanism controlled thereby at the second position, means for releasing the disc to permit the same to rotate through a definite arc to the second position in accordance with its bias, whereby a time interval in the control of the said switch mechanism is introduced by the time taken by said disc in rotating from the first position to the second position, and means for varying the arc of rotation of said disc whereby the time interval is varied.

7. A time element device for controlling electric circuits comprising a rotatably mounted disc adapted to be held at one position against its bias to a second position, switeh'mechanism controlled thereby at the second position, means for releasing the disc to permit the same to rotate to the second position in accordance with its bias, whereby a time interval in the control of the said switch mechanism is introduced by the time taken by said disc in rotating from the first position to the second position, and means controlled by the releasing means for restoring the disc to the first position.

8. A time element device for controlling electric circuits comprising an unbalanced rotatably mounted fly-wheel adapted to be held at an unstable position, switch mechanism controlled thereby in the stable position of the fly-wheel, means for releasing the fiy-wheel to permit the same to rotate to the stable position, whereby a time interval in the control of the said switch mechanism is introduced by the time taken by said flywheel in rotating from the unstable to' the stable position, and electroresponsive means for varying the said time interval.

9. A time element device for controlling electric circuits comprising a rotatably mounted disc adapted to be held at one position against its bias to a second position, circuit making contacts controlled thereby at the second position, electromagnetically controlled means for releasing the disc to permit the same to rotate to the second position in accordance with its bias, whereby a time interval in the control of the said contacts is introduced by the time taken by said disc in rotating from the first position to the second position, and an electromagnet energized responsively to predetermined conditions for temporarily retarding the rotation of the disc tov increase the time interval.

10. A time element device for controlling electric circuits,comprising a stationary contact, an unbalanced fly-whel disc rotatably mounted bearing a contact arranged to engage with said stationary contact when said disc rotates, and means for controlling the rotation of the disc.

11. A time element device for controlling electric circuits, comprisin a stationary contact, an unbalanced fiy-w eel disc rotat ably mounted bearing a contact arranged to engage with said stationary contact when said disc rotates and means for controlling the engagement ofthe contacts.

12. A time element device for controlling electric circuits, comprising a stationary contact, an unbalanced fly-wheel disc rotatably mounted bearing a contact arranged to engage with said stationary contactwhen the disc rotates, means for stoppin the disc at the point of engagement of sai contacts 31d means for controlling the rotation of the 13. A time element device for controlling electric circuits, comprising a stationary contact, an unbalanced fly-wheel disc rotatably mounted bearing a contact arranged to en- 'age with said stationary contact when the disc rotates, means for stopping the disc at the point of en agement of said contacts and means for isengaging the contacts and holding the disc in unstable equilibrium 14. A time element device for controlling I electric circuits, comprising a stationary contact, an unbalanced fly-wheel disc rotatably mounted bearing a contact arranged to engage with said stationary contact when the disc rotates, means for stopping the disc at the point of engagement of said contacts, means for disengaging the contacts and holding the disc in unstable equilibrium and means for releasing the disc to permit the disc to rotate from such position of unstable equilibrium.

15. A time element device for controlling electric circuits, comprising a stationary contact, an unbalanced fly-wheel disc rotatably mounted bearing a contact arranged to engage with said stationary contact when the disc rotates, means for stopping the disc at the point of engagement of said contacts, means for disengaging the contacts and holding the disc in unstable equilibrium, means for releasing the disc to permit the disc to rotate from such position. of unstable equilibrium and means for varying the time (iinterval introduced by the rotation of the '16. A time element device for controlling.

electric circuits, comprisin a stationary contact, an unbalanced fiy- 1eel disc rotatably mounted bearing a contact arranged to engage with said stationary contact when the disc rotates, means for stopping the disc at the point of engagement of said contacts, means for disengaging said contacts and holding the disc in unstable equilibrium, means for releasing the disc to permit the disc to rotate from such position of unstable equilibrium and means for varying the speed of rotation of the disc when released.

17. A time element relay comprisin a stationary contact, an unbalanced fly-w eel disc rotatably mounted bearing a contact arranged to engage with said stationary contact when the disc rotates, means for stopping the disc at the point of engagement of sai contacts, means for disengaging said contacts and holding the disc in unstable equilibrium, an electromagnet for releasing the disc to permit the disc to rotate from the position of unstable equilibrium, and an electromagnet having means for retarding the movement of the disc when released.

18. A time clement device for controlling electric circuits comprisin a stationary contact, an unbalanced fly-w eel disc rotatably. mounted bearing a contact arranged to enge with said stationar contact when the isc rotates, and means or disengaging the contacts and holding the disc in unstable equilibrium comprising a spring, a trigger moved thereby and a pin on the disc near the periphery of the disc engaged by the trigger until the contacts separate, and another pin on the disc further from the periphery of the disc engaged by said trigger to complete the movement of the disc to the unstable position.

In witness whereof, I have hereunto set my hand this 23rd da of June 1919.

ROBE T H. MQLAIN. 

